Cancer is the result of an accumulation of oncogenic mutations. The vast majority of these oncogenic mutations are point mutations. The advances over the last decade have identified a number of these oncogenic point mutations and established their involvement in the initiation and progression of benign and malignant tumors. However, this knowledge has not significantly improved cancer morbidity or mortality. We are interested in determining if oncogenic point mutations can he used for the early detection of colorectal idenomatous polyps and cancers in patients at risk. To address these issues, we are developing two separate techniques for the rapid detection of mutations in oncogenic loci: l) polymerase chain reaction / ligase chain reaction (PCR/LCR) for the detection of mutations in tumor tissue; and 2) polymerase chain reaction / restriction encodnuclease / ligase chain reaction (PCR/RE/LCR) for the detection of mutations present in one cell in 10[6] or l0[7] normal cells. PCR/LCR techniques appear to detect mutations at the sensitivity of only about one in 10[2], while PCR/RE/LCR has already detected one mutation-bearing cell in the presence of 10[7] normal cells. In order to demonstrate the usefulness of these techniques for the early detection of tumors in patients at risk of colon cancer, panels of PCR/LCR and PCR/RE/LCR are being established for Kirsten-ras codons 12, 13, and 61, codons 175,245,248,249,273, and 282 of p53, and the possible hotspot codons 1061 and 1309 of the APC gene. These panels will be used to evaluate samples taken from patients in four separate groups composing a cross-sectional study of individuals with cancer, or of high, modest, or low cancer risk. The question of whether or not diagnostic mutations can be detected in exfoliated colonic mucosa epithelial cells, will be answered by the initial determination of clonal mutations in resected tumor specimens and the subsequent search for these index mutations in stool, colonic lavage, and random rectal biopsies taken before and after resection. The optimal specimen (stool, colonic lavage, or rectal biopsy) for the detection of diagnostic mutations will be determined. Sufficient numbers of patients will be enrolled to determine the value of this approach for clinical care of patients at risk of colon cancer. These highly sensitive PCR/LCR mutation detection and identification techniques will also enable the study and monitoring of individual patients.